The present invention relates to a communication installation on sites, some portions of which are formed by underground galleries, for information exchanges between members of the personnel and typically between members of the personnel and the outside.
The invention is particularly suitable for use in mines where communications raise particular problems. The advance of the working face constantly modifies the position of the miners who are working there. The galleries often have bends which greatly attenuate microwave free propagation by UHF link. Mining regulations limit to a low value the radioelectric power radiated by the equipment.